Red paint gets its color from pigments. Pigments are powders made up of particles that absorb some colors of light and reflect others. The pigments used to make red paint selectively absorb blue and green light, while reflecting wavelengths in the red area of the visible spectrum. This causes our eyes to perceive the paint as red.
There are several common red pigments used in paints, each with their own characteristics and manufacturing process. Some key red pigments include:
Iron Oxide Reds
One of the most common red pigments is iron oxide, known as rust when in its natural form. Iron oxide pigments produce colors ranging from light red to deep, dark red.
Natural iron oxides have been used as pigments since prehistoric times. Prehistoric cave paintings in Europe were often done using iron oxide pigments such as red ochre.
Modern iron oxide pigments are synthetically manufactured. The main types used in paints include:
– Red 101 (Fe2O3) – Produces bright reddish tints
– Red 102 (Fe2O3 – MnO2) – Darker red shades
– Red 104 (Fe2O3 – Cr2O3) – Dark red pigment
Advantages of iron oxide pigments:
– Inexpensive to produce
– Chemically stable, lightfast, and weather resistant
– Non-toxic
– Easy to disperse in paint
Limitations:
– Produce earthy, muted shades of red compared to other pigments
– Low tinting strength, requiring high concentrations for vivid reds
Cadmium Red
Cadmium red is produced by combining cadmium sulfide with selenium. It yields bright, pure reds with a slight orange undertone.
Cadmium red has been valued by artists for centuries for its brilliance and opacity. However, cadmium pigments are toxic due to the metal cadmium. Many regions have restricted the use of cadmium in artists’ paints and commercial coatings.
There are a few varieties of cadmium red pigments:
– Cadmium red light – Vivid, opaque red
– Cadmium red deep – Deeper, more intense red
– Cadmium red medium – In between light and deep
Advantages of cadmium reds:
– Intense, vivid red with excellent tinting strength
– Opaque, helps hide substrates
Disadvantages:
– Toxicity concerns due to cadmium content
– Relatively expensive
Naphthol Reds
Naphthol reds are synthetic organic pigments made by combining different chemical components. By varying the components, a wide range of vivid red hues can be produced.
Some examples of naphthol reds include:
– Naphthol red – Bright red shade
– Pyrrole red – Bluish undertone
– Permanent garnet – Yellowish undertone
Advantages of naphthol reds:
– Very bright, intense reds with excellent tinting strength
– Transparent, useful for glazes
– Non-toxic
Disadvantages:
– Can fade over time if not properly formulated
– Some varieties are not lightfast
– Cost is higher than inorganic reds
Quinacridone Reds
Quinacridones are another important class of synthetic organic pigments used to produce strong red colors. They are made by heating certain dioxazine compounds.
The main quinacridone reds are:
– Quinacridone magenta – Bluish undertone
– Quinacridone red – Balanced pure red
Advantages:
– Excellent lightfastness and weather resistance
– Bright, transparent reds with fantastic tinting strength
– Non-toxic
Disadvantages:
– Relatively expensive to produce
– Can be difficult to disperse well in some paint bases
Alizarin Crimson
Alizarin crimson is a transparent, cool red pigment made from the roots of the madder plant. It has been used as a pigment for centuries and was a very popular red pigment before synthetic reds were developed.
Today, alizarin crimson is still produced for artists’ paints using the original madder synthesis process. It produces deeper, richer hues than synthetic versions.
Advantages:
– Deep, rich red color
– Transparent, useful for glazing techniques
– Traditionally prized by artists
Disadvantages:
– Expensive due to natural madder synthesis
– Very weak tinting strength
– Fugitive if not properly formulated
Vermilion
Vermilion is a brilliant orange-red pigment made from the mineral cinnabar. It has been used since ancient times and was very important in medieval and Renaissance painting.
True, natural vermilion comes from cinnabar ore. However, most modern vermilion is synthetically produced for toxicity reasons.
Advantages:
– Vivid, opaque orange-red color
– Good lightfastness
– Historically important pigment
Disadvantages:
– Toxicity of cinnabar-based vermilion
– Synthetic versions are not as deep and rich
– Expensive compared to other reds
Red Lake Pigments
Red lake pigments are produced by precipitating coloring agents onto a substrate, typically alumina hydrate. Some examples include:
– Madder lake – From the roots of the madder plant
– Carmine lake – From cochineal insects
– Crimson lake – From the kermes insect
Lake pigments produce transparent, thin film red colors. They have very low tinting strength on their own and are often used as glazes over other reds.
Advantages:
– Provide transparent, glazing reds
– Are non-grainy when used properly
Disadvantages:
– Extremely poor tinting strength
– Color is dependent on lake substrate
– Some varieties are fugitive
Red Dyes
Soluble red dyes are sometimes used as colorants in paints, particularly water-based acrylics. They produce transparent colors and often lack the lightfastness of pigments.
Common red dyes used in paints include:
– Allura Red AC – Orangey-red food dye
– Rhodamine B – Pinkish dye used in cosmetics
– Sudan Red – Solvent-soluble orange dye
Advantages:
– soluble colorants suitable for water-based paints
– transparent, glazing effects
Disadvantages:
– Poor lightfastness
– Bleed and fade over time
– Limited to thin washes and glazes
Mixing Other Colors to Make Red
In theory, red can be mixed from combining other primary paint colors together. However, in practice this does not produce optimal red colors.
Mixing paint pigments causes a darkening and dulling effect. Mixing yellow and magenta paint creates a dark reddish-brown color, not a bright pure red. Additional white paint must be added to lighten and brighten the mixture.
Painters may utilize color mixing to adjust red hues. But premixed reds with pure red pigments give the best results.
Here is a table showing typical results mixing paints to try to produce red:
| Paints Mixed | Resulting Color |
| Magenta + Yellow | Dark dull reddish brown |
| Magenta + Yellow + White | Dull pinkish red |
| Cadmium Red + Viridian | Dark muted red |
| Alizarin Crimson + Lemon Yellow | Transparent orange red |
As seen above, mixing paints to create red typically produces muddy, dark, or otherwise inferior results compared to pure red pigments. Preferred red paints utilize strong, lightfast red pigments rather than mixing.
Choosing the Best Red Paint
Artists or painters selecting a red paint should consider the following criteria:
– **Pigments Used** – Opt for modern synthetic reds over toxic cadmiums and expensive natural pigments. Quinacridones, naphthols, and synthetic iron oxides offer excellent reds.
– **Lightfastness** – Make sure the red pigments have excellent lightfastness ratings to prevent fading.
– **Transparency vs. Opaqueness** – Select transparent reds for glazing and opaque reds for coverage.
– **Tinting Strength** – Strong tinting reds allow vivid colors even when mixed with white or other paints.
– **Cost and Availability** – Balance performance against cost constraints.
– **Hue** – Pick the specific red hue (orangey, blueish) needed for your painting.
The best all-around red paint is often a modern synthetic red with good lightfastness and tinting strength. Quinacridone or naphthol reds offer excellent performance for most painting needs.
Historic and Modern Uses of Red Paint
Red pigments and paints have been used by artists and craftsmen throughout history. Here are some notable examples:
– **Prehistoric Cave Paintings** – Iron oxide reds featured prominently in paintings from over 40,000 years ago, such as those in the Chauvet Cave.
– **Ancient Greek and Roman Painting** – Vermilion and red ochre were used, along with plant-based red lakes. Egyptian red madder lake dates back to this era.
– **Medieval Illuminated Manuscripts** – Luxurious gold leaf and red paints highlighted important text and imagery. Cinnabar vermilion and kermes crimson lake were popular.
– **Renaissance Painting** – Vermilion, crimson lake, and madder lake provided rich reds. Vermilion was very expensive, reserved for the most important subjects.
– **Impressionist Paintings** – Emerging synthetic reds partially replaced historic pigments. Cadmium red appeared in the 1800s.
– **Modern Art** – 20th century artists embraced brighter synthetic reds like quinacridone and naphthol, moving away from natural pigments.
Today, vibrant synthetic organic reds and modern hues like quinacridone magenta dominate painting. But traditional natural reds are still available for those seeking an historic look.
Manufacturing Red Paint
Commercial red paint is made by incorporating pure red pigments into paint bases along with additional components. Here is a typical manufacturing process:
1. **Pigment Production** – Raw source materials are processed to synthesize red pigment particles like iron oxides, cadmium red, or quinacridones.
2. **Dispersion** – The dry pigment powder is mixed with water, solvent, and dispersing agents to break up agglomerates into a uniform pigment dispersion.
3. **Grinding** – The coarse pigment dispersion is further ground in mills to break down pigment particles to a fine particle size.
4. **Letdown** – The fine pigment grind is blended with the appropriate paint base – oil, alkyd, acrylic emulsion, etc. Additional ingredients are added to produce the desired paint consistency and working properties.
5. **Quality Control** – The finished paint is checked to ensure correct color, application properties, and stability.
6. **Packaging** – Once approved, the red paint is filled into retail-ready metal cans, plastic containers, or tubes.
High quality red paint relies on optimal pigment dispersion and incorporation into the paint base. Poor dispersion leaves coarse particles resulting in low color strength. Careful manufacturing helps deliver vivid, consistent red paint.
Uses of Red Paint
Thanks to its strong visual impact, red paint has endless uses including:
– **Fine Art** – Red is a dominant color in painting and other fine art fields. Both cool and warm reds are extensively used.
– **Automotive Finishing** – Cars, motorcycles, and other vehicles are often finished with reds ranging from bright candy apple red to deep burgundy.
– **Home Decor** – Red paint is frequently used to give walls, furniture, cabinets, and decor details a bold pop of color.
– **Industrial Coatings** – Red provides high visibility on safety equipment, machinery, pipelines, and commercial structures.
– **Toys** – Vibrant reds decorate toys, games, models, and craft supplies to appeal to all ages.
– **Cosmetics** – Reds provide essential colors for makeup, nail polish, lipstick, and face paint. Water-soluble dyes are often used.
– **Clothing** – Red dyes color fabrics ranging from sport team uniforms to fashion garments to leather goods.
With its versatility and visual power, red paint brings color and excitement to nearly any field imaginable.
Conclusion
Red paint gets its vibrant color from pure red pigments, most commonly modern synthetic pigments for their optimized performance. By selecting the right red pigment and paint base, strong, stable, safe red paints can be produced for any application. Red continues to be one of the most visually striking colors, ensuring red paints will maintain their importance for artists and industries alike.
